1. Field of the Invention
This invention relates to antibodies specific for proteins differentially expressed in normal and tumor or precancerous cells and tissues. The invention more specifically relates to antibodies that are immunologically specific for a particular human protein, ARL-1 (also referred to as AKR1B10), a species of protein in the aldo-keto reductase (AKR) superfamily. The invention particularly relates to polyclonal antisera, monoclonal antibodies and fragments and derivatives thereof that are immunologically specific for ARL-1 differentially expressed in normal and tumor or precancerous cells and tissues of the gastrointestinal tract. Methods for making and using said antibodies are also provided.
2. Summary of the Related Art
Cancer remains one of the leading causes of death in the United States, with colon cancer representing the second leading cause of cancer death in the U.S. (Nyska et al., 2001, Arch Toxicol. 75: 618-624). It has long been recognized that development of cancer, particularly cancers that occur in later life such as colon cancer, are in part the result of lifelong exposure to environmental carcinogens. Surprisingly, many of these carcinogens are contained in or produced from foods and other natural products. See, Ames, 1983, Science 221: 1256-1264
For example, electrophilic carbonyls are constantly produced during metabolism of carbohydrate and lipid (Davydov et al., 2004, Exp Gerontol. 39: 11-16; De Bont & van Larebeke, 2004, Mutagenesis 19: 169-185; Choudhary et al., 2005, Toxicol Appl Pharmacol. 204: 122-134, 2005). Carbonyls also widely exist in air, water, and various foodstuffs and beverages (Bowmer & Higgins, 1976, Arch Environ Contam Toxicol. 5: 87-96; Schuler & Eder, 2000, Arch Toxicol. 74: 404-414; Seaman et al., 2006, Anal Chem. 78: 2405-2412). Human exposure to carbonyls occurs in consumption of fruits, vegetables, fish, meat, and alcoholic beverages, such as wine and whisky (Bowmer & Higgins, 1976, Id; Uchida et al., 1998, Proc Natl Acad Sci USA 95: 4882-4887). Indeed, carcinogenic methylglyoxal is a constituent of daily consumed coffee, whereas carcinogenic crotonaldehyde is widely present in fruit (5.4-78 μg/kg), vegetables (1.4-100 μg/kg), fish (71.4-1000 μg/kg), meat (10-270 μg/kg), and alcoholic beverages, such as wine (300-700 μg/L) and whisky (30-210 μg/L) (Schuler et al., 2000, Arch Toxicol. 74: 404-414.).
Because of their reactivity, carbonyls can interact with free amino and sulfhydryl groups of proteins, peptides and amino acids, forming covalently modified adducts (Davydov et al., 2004, Id.; Vasiliou et al., 2000, Chem Biol Interact. 129: 1-19; Hashimoto et al., 2003, J Biol Chem. 278: 5044-5051; Okada et al., 1999, J Biol Chem. 274: 23787-23793; Uchida et al., 1992, Proc Natl Acad Sci USA, 89: 5611-5615). These non-specific, covalent modifications may cause protein dysfunction, resistance to intracellular proteolysis, or depolymerization. Protein adducts may also act as secondary messengers, autoantigens, or inhibitors of proteosomes, causing cellular damage and/or autoimmune disorders.
Electrophilic carbonyls can also react with nucleic acids (DNA), forming covalently modified DNA adducts. DNA adducts can block DNA semiconservative replication performed by DNA polymerase, arrest transcription driven by RNA polymerase, and cause DNA mutations and breaks (De Bont & van Larebeke, 2004, Id.; Yang et al., 2002, Biochemistry 41: 13826-13832; Hou et al., 1995, Environ Mol Mutagen 26: 286-291; Nagy et al., 2005, Carcinogenesis 26: 1821-1828; Cline et al., 2004, Proc Natl Acad Sci USA 101: 7275-7280, 2004). Documented evidence has indicated the pathogenic effect of carbonyl-derived DNA modifications, resulting in mutagenesis, carcinogenesis, and other age-related diseases (Davydov et al., 2004, Id.; Yang et al., 2002, Biochemistry 41: 13826-13832; Nagy et al., 2005, Carcinogenesis 26: 1821-1828; Ames, 1983, Id.).
Consequently, electrophilic dietary carbonyls are important pathogens of gastrointestinal (GI) diseases, including neoplasms (Homann et al., 2000, Int J Cancer 86: 169-173; Nyska et al., 2001, Id.; Korenaga et al., 2002, J Surg Res 102: 144-149; Schaeferhenrich et al., 2003, Mutat Res. 526: 19-32). Via food consumption, GI cells are repeatedly exposed to various reactive carbonyls (Ames, 1983, Id.: Fujioka & Shibamoto, 2004, Lipids 39: 481-486, 2004). This long term and cumulative carbonyl exposure, even though minimal, may eventually cause carcinogenic changes of GI cells. Indeed, exposure of F344 rats to 2,4-hexadienal induced stomach hyperplasia, squamous papilloma, and carcinoma in rats; and high levels of malondialdehyde (MDA) in colonic mucosa was pathogenically related to neoplastic lesions in ulcerative colitis (Korenaga et al., 2002, Id.; Nyska et al., 2001, Id.). In addition, local accumulation of acetaldehyde, microbially produced after alcohol consumption, has been considered a carcinogenic factor for colon and gastric cancers (Homann et al., 2000, Id.; Salaspuro, 2003, Best Pract Res Clin Gastroenterol. 17: 679-694).
Nevertheless, little is known of the GI-specific protective mechanisms against carcinogenic lesions induced by dietary carbonyls. Aldehyde dehydrogenase and glutathione-S-transferase (GST) are important enzymes in elimination of intracellular carbonyls by catalyzing carbonyl oxidation to carbonic acids or conjugation with glutathione, but no evidence demonstrates their GI-specificity (Vasiliou et al., 2000, Id.; Sladek, 2003, J Biochem Mol Toxicol. 17: 7-23; Coles & Kadlubar, 2003, Biofactors 17: 115-130; Sharma et al., 2004, Antioxid Redox Signal. 6: 289-300, 2004).
There is a need in this art to identify endogenous protective mechanisms and proteins involved in such mechanisms. There is further a need in this art to identify whether differential expression of proteins involved in protecting gastrointestinal cells and tissues from the mutagenic and carcinogenic effects of food-related reactive carbonyls provides a marker for cells and tissues at risk for neoplastic transformation and tumor formation, or identifies cells having resistance to anticancer chemotherapeutic drugs, or provides a target for therapeutic and prevention interventions in cancer or precancerous states.